CA1112352A - Test head for ultrasonic testing of structural material - Google Patents
Test head for ultrasonic testing of structural materialInfo
- Publication number
- CA1112352A CA1112352A CA305,016A CA305016A CA1112352A CA 1112352 A CA1112352 A CA 1112352A CA 305016 A CA305016 A CA 305016A CA 1112352 A CA1112352 A CA 1112352A
- Authority
- CA
- Canada
- Prior art keywords
- transducer
- reflector
- test
- calibration
- path
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H3/00—Measuring characteristics of vibrations by using a detector in a fluid
- G01H3/005—Testing or calibrating of detectors covered by the subgroups of G01H3/00
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/24—Probes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/30—Arrangements for calibrating or comparing, e.g. with standard objects
Abstract
ABSTRACT OF THE DISCLOSURE
Disclosed is a test head for ultrasonic testing of structural ma-terials. The test head includes its own calibration device in the form of a wire or a bore in front of the transducing surface so that a distinguish-able calibration echo is always available. This eliminates the need to cal-ibrate the head by using a reference test object.
Disclosed is a test head for ultrasonic testing of structural ma-terials. The test head includes its own calibration device in the form of a wire or a bore in front of the transducing surface so that a distinguish-able calibration echo is always available. This eliminates the need to cal-ibrate the head by using a reference test object.
Description
The present inventioll relates to improvements in the non-destructive test.ing of structural ma-terials, and more particularly, -the in-vention relates to an u]trasonic test head and transducer.
Ultrasonic test equipment for structure parts such as pipes or the like, usually require a particular orientation of such parts relative to the test transducers, particularly if a part mo~es while it is being ex-amined. Moreover, the equipmen-t requires calibra-tion in order to permit interpretation of any signal being picked up. Particularly, the test equip-ment includes ultrasonic transducers co~lpled in a suitable manner to the test object and launch test signals into that object. The latter will re-turn echo signals which have different significance. Legitimate boundaries as ~ell as internal inhomogeneities, flaws, cracks, etc., all may produce echos. The transit time as well as the amplitude of such echos constitute informative parameters ~Thich require interpretationO The transducer oper-ation, the signal proclucing electronics as well as the signal receiving and processing electronics, contribute to the wave shape of the signals as ul-timately received and evaluated. It is, therefore, necessary to calibrate the transducers. For this, it has been necessary in the past to couple the transducer to a reference ob~ect or aummy preferably ha~ing dimensions, con-tour and acoustic properties equal to or at least closely matching the cor-responding features of the test objects. ~he reference ob~ect is not only used for purposes of signal level calibration, gain adjustment, sensitivity and threshold adjustments, etc., but also for purposes of determining the requisite angles of incidence for the test beams, the skip distance in the case of testing pipes or plates~ and the requisite actual distance needed for a specific task.
The use of such calibration ob~ects was found to be a problem in so~e instances. Take, for example, the following situation. It appears that a best suited reference ob~ect is a test object knoT~n, e.g. to have no ; 30~ defects. It ma~ be the first or one of the first ob~ects made, or a portion , of an object made in a first production run, being a part oE a pilot series, etc. The thus chosen object is now provided with a definite "defect" to be used as a reference in the calibration procedure. It was found that this defect simulation is not sufficiently accurate nor are such simulated errors accurately reproducible if different reference objects are made. ~nother point is the delay incurred when the calibration object is taken from the production which must be halted until the calibration has been completed.
A test procedure has been suggested (United States-Patent ~910~,326) -which eliminates the disadvantages outlined above by using a particular reference object or dummy in a separate calibration installation to ascertain operating parameters for the test electronics as well as the test heads, simulating true test conditions. A particular test standard or reference element (to be distinguished from the reference object or dummy) is then used in the calibration instal]ation as adjusted to generate particular responses.
That standard is then temporarily in~talled in the on-line test equipment and its electronics is then adjusted on the basis of the responses one obtains with the standard in comparison with the responses the same standard involved in the calibration electronics. This procedure operates quite satisfactorily, particularly because the calibration can be made ahead of production runs.
It is an object of the present invention to further simplify cali-bration procedure in ultrasonic test equipment using an approach that is different as compared with prior practice.
Thus, in accordance with one broad aspect of the invention there is provlded a transducer head for ultrasonic testing of structllral materials having a transducing surface, comprising:
a means for defining an acoustic wave propagative path in front of the surface; and a calibration reflector disposed across the path in front oE the said surface and at a distance therefrom for intercepting a central portion and reflecting a small portion of any ultrasonic energy launched by the trans ducer, but permitting the major port:ion of that energy to pass said reflector ~ .
~bd ;3~ ;~
on both sides due to the extens:ion of the reflector across the path oE the energy.
In accordance with another broad aspect of the invention there is provided a method of operating an ultrasonic transducer for testing structur-al materials~ including coupling the transducer to a test object, the trans-ducer being connected to test electronics, the improvement comprising:
providing a permanently installed reference reflector between an active transducing surface and the test object, spaced from both of them and extending across a path from the transducing surface for intercepting a central portion of a beam of ul-trasonic energy when launched by the trans-ducer;
extracting echo signals from the transducer, resulting from the reflection of ultrasonic energy by the reflector, including distinguishing the echo signal from others on the basis of transit time difference; and using the thus distinguished echo signal for calibration, including calibration of the response of the test electronics.
In accordance with the preferred embodiment of the present inven-tion, it is suggested to incorporate a calibration device in each transducer of an ultrasonic test apparatus in that such a transducer is provided with ~
a partial reflector in front of its transducing surface, but sufficiently ~ -far from the interface with the test object. This reflector provides an echo for each pulse launched which echo can be used Eor calibration. By way of example, the reflector may be a wire or a bore in a solid transmissive medium in front Oe the transducing surface. The ma~or portion of transduc-ing energy is always permitted to pass so that the "cali~bration echo" does not subtract any significant amount of test energy from the launched pulse.
The calibration procedure is, therefore, greatly simplified and no longer separated from the test runs. Moreover, the calibration echo is always available and readily diatinguishable from o~her echos on account of the transit time. The calibratlon~ may, in fact, become a part of the test pro- -cedure itself so that updating and any readju~tment can be made at any time ai~J~
during testing without interruption of the on-line operation or any portion thereof.
While the specification concludes with cla:ims particularly point-ing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the obJects and ~eatures of -the in~ention and further objects, ~eatures and advantages thereof will be better understood from the following description taken in connec-tion with the accompan~ing drawings in which:
Figure 1 is a cross-sec-tion through a test head supplemented in accordance with the preferred embodiment o~ the invention, showing a partic-ular example;
Figure 2 is a similar cross~section showing a modification but still within the purview of the preferred embodiment.
Proceeding to the detailed description of the drawings, Figure 1 illustrates an ultrasonic transducer 1, having an active vibrating or ex-terna~ly stimulated ~ibrating element 2, respectively, ~or launching or re-ceiving ultrasonic signals. This portion of the transducer is conventional;
i.e. it is constructed to emit ultrasonic waves upon being electrically stimulated, while generating electrical signals when being acoustically stimulated. Also conventional is the use of electronic circuitry in con-~unction with that transducer including particularly circuitry which switch-es over ~rom the transmitter mode to the recei~er mode once an ultrasonic pulse has been launched.
'~he transducer is contained in a sleeve 3 for purposes of mounting.
The front of the sleeve projects beyond the transducing surface 2'. Con-ceivably, the space adjacent to that surface 2' is filled with water during test operations. The front end of that sleeve may engage the test ob~ect, however5 the inter~ace may be somewhat fur-ther away still. The sleeve should have poor propagati~e properties as to acoustic waves, or at least may be provided with some attenuating means, so -that ultrasonic ~a~es are b3~
not launched via the sleeve 3. A relati~ely thin wire 4 is placed dia-metrally across -the space in ~ront of surface 2', and at a particular1 well defined distance therefrom. The area covered by the ~ire 4 in front of sur-~ace 2' is small in relation to -the area of that surf'ace. Since the prop-agation path from the vibrating element to the wire has good propagative properties, there is little attenuation and a ~inite amoun-t of acoustic en-ergy i5 reflected back to the transducerO That amoun-t will produce a de~-inite response, i.e. it is suf'~iciently strong, being, as far as the ampli-tude is concerned, o~ the order of flaw echos, which the transducer may recei~e when coupled to a test ob~ect. On the other hand, the partial re-~lection on wire L~ diminishes the launched energy to a ~rery small extent only so that the test is not inter~erred wi-th.
In operation, the head is depicted, i~e. including its calibration reflector element 4, is installed in the test equipment which is now cali-brated in situ. The response o~ the electronics, with head installed, to the echo from the wire is and remains an operating parameter. During test runs there will always be an echo ~rom wire 4 so that the equipment can be recalibrated whenever needed.
The echo can actually be used in each test cycle as one o-~ the measuring parameters. Slnce the wire 4 is also spaced ~rom the interface between, on one hand, the transaucer and the coupler ~luid, and~ on the other hand~ the test obJect, the echo from wire 1I can readily be distin-guished ~rom any other echos on the basis o~ the transit time. The wire echo will occur at a rather precisely de~ined period of time following launching and positively before~ e.g. a ~ront wall echo on test objects' sur~ace. The wire ~ must be spaced su~iciently ~ar ~rom sur~ace 2' so that the transducer can readily be switched in time ~rom the transmitter -to the receiver mode. Also, the transducer as such should have recovered be~ore the calibration echo arrives.
Since the calibration ~eature becomes a permanent part o~ the test head, there is an inheren-t compensation oP any manufacturing tolerances.
Also, any external interferences with the operation can readily be recog~
nized by, e.g. a change in the amplitude of the calibration wire echo.
Moreover, the initialization and set up procedure oP the test equipment is shortened.
Figure 2 illustrates a variant in the construction -to be used either when coupler fluid is not employed or i~ one does not wish to extend any coupler fluid directly to the active transducing surface 2'. The trans-ducer jacket has been extended here in forward direction, though a sleeve, such as 3 of Figure 1, could also be used. The front end of the transducer jacket is filled with a plastic material 6 of particular acoustic properties.
The material should not attenuate the acoustic energy, exhibit little dis-persion and should not tend to reverberate. One can use here, for example, material sold under the trade mark "Plexiglas".
The material 6 is provided simply with a bore 5 extending in dia-metrical direction across the space in Pront oP the transducing surface 2' and also at a well de~ined distance there~rom. The bore 5, in this case, acts as a calibration and reference reflector just as wire L~ in Figure 1.
~he advantages and Peatures outlined above are also applicable here.
ZO l~e invention is not limited to the embodiments described above but all changes and modifications thereof not constituting departures from the ~pirlt a d scope of the invention are intended to be included.
Ultrasonic test equipment for structure parts such as pipes or the like, usually require a particular orientation of such parts relative to the test transducers, particularly if a part mo~es while it is being ex-amined. Moreover, the equipmen-t requires calibra-tion in order to permit interpretation of any signal being picked up. Particularly, the test equip-ment includes ultrasonic transducers co~lpled in a suitable manner to the test object and launch test signals into that object. The latter will re-turn echo signals which have different significance. Legitimate boundaries as ~ell as internal inhomogeneities, flaws, cracks, etc., all may produce echos. The transit time as well as the amplitude of such echos constitute informative parameters ~Thich require interpretationO The transducer oper-ation, the signal proclucing electronics as well as the signal receiving and processing electronics, contribute to the wave shape of the signals as ul-timately received and evaluated. It is, therefore, necessary to calibrate the transducers. For this, it has been necessary in the past to couple the transducer to a reference ob~ect or aummy preferably ha~ing dimensions, con-tour and acoustic properties equal to or at least closely matching the cor-responding features of the test objects. ~he reference ob~ect is not only used for purposes of signal level calibration, gain adjustment, sensitivity and threshold adjustments, etc., but also for purposes of determining the requisite angles of incidence for the test beams, the skip distance in the case of testing pipes or plates~ and the requisite actual distance needed for a specific task.
The use of such calibration ob~ects was found to be a problem in so~e instances. Take, for example, the following situation. It appears that a best suited reference ob~ect is a test object knoT~n, e.g. to have no ; 30~ defects. It ma~ be the first or one of the first ob~ects made, or a portion , of an object made in a first production run, being a part oE a pilot series, etc. The thus chosen object is now provided with a definite "defect" to be used as a reference in the calibration procedure. It was found that this defect simulation is not sufficiently accurate nor are such simulated errors accurately reproducible if different reference objects are made. ~nother point is the delay incurred when the calibration object is taken from the production which must be halted until the calibration has been completed.
A test procedure has been suggested (United States-Patent ~910~,326) -which eliminates the disadvantages outlined above by using a particular reference object or dummy in a separate calibration installation to ascertain operating parameters for the test electronics as well as the test heads, simulating true test conditions. A particular test standard or reference element (to be distinguished from the reference object or dummy) is then used in the calibration instal]ation as adjusted to generate particular responses.
That standard is then temporarily in~talled in the on-line test equipment and its electronics is then adjusted on the basis of the responses one obtains with the standard in comparison with the responses the same standard involved in the calibration electronics. This procedure operates quite satisfactorily, particularly because the calibration can be made ahead of production runs.
It is an object of the present invention to further simplify cali-bration procedure in ultrasonic test equipment using an approach that is different as compared with prior practice.
Thus, in accordance with one broad aspect of the invention there is provlded a transducer head for ultrasonic testing of structllral materials having a transducing surface, comprising:
a means for defining an acoustic wave propagative path in front of the surface; and a calibration reflector disposed across the path in front oE the said surface and at a distance therefrom for intercepting a central portion and reflecting a small portion of any ultrasonic energy launched by the trans ducer, but permitting the major port:ion of that energy to pass said reflector ~ .
~bd ;3~ ;~
on both sides due to the extens:ion of the reflector across the path oE the energy.
In accordance with another broad aspect of the invention there is provided a method of operating an ultrasonic transducer for testing structur-al materials~ including coupling the transducer to a test object, the trans-ducer being connected to test electronics, the improvement comprising:
providing a permanently installed reference reflector between an active transducing surface and the test object, spaced from both of them and extending across a path from the transducing surface for intercepting a central portion of a beam of ul-trasonic energy when launched by the trans-ducer;
extracting echo signals from the transducer, resulting from the reflection of ultrasonic energy by the reflector, including distinguishing the echo signal from others on the basis of transit time difference; and using the thus distinguished echo signal for calibration, including calibration of the response of the test electronics.
In accordance with the preferred embodiment of the present inven-tion, it is suggested to incorporate a calibration device in each transducer of an ultrasonic test apparatus in that such a transducer is provided with ~
a partial reflector in front of its transducing surface, but sufficiently ~ -far from the interface with the test object. This reflector provides an echo for each pulse launched which echo can be used Eor calibration. By way of example, the reflector may be a wire or a bore in a solid transmissive medium in front Oe the transducing surface. The ma~or portion of transduc-ing energy is always permitted to pass so that the "cali~bration echo" does not subtract any significant amount of test energy from the launched pulse.
The calibration procedure is, therefore, greatly simplified and no longer separated from the test runs. Moreover, the calibration echo is always available and readily diatinguishable from o~her echos on account of the transit time. The calibratlon~ may, in fact, become a part of the test pro- -cedure itself so that updating and any readju~tment can be made at any time ai~J~
during testing without interruption of the on-line operation or any portion thereof.
While the specification concludes with cla:ims particularly point-ing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the obJects and ~eatures of -the in~ention and further objects, ~eatures and advantages thereof will be better understood from the following description taken in connec-tion with the accompan~ing drawings in which:
Figure 1 is a cross-sec-tion through a test head supplemented in accordance with the preferred embodiment o~ the invention, showing a partic-ular example;
Figure 2 is a similar cross~section showing a modification but still within the purview of the preferred embodiment.
Proceeding to the detailed description of the drawings, Figure 1 illustrates an ultrasonic transducer 1, having an active vibrating or ex-terna~ly stimulated ~ibrating element 2, respectively, ~or launching or re-ceiving ultrasonic signals. This portion of the transducer is conventional;
i.e. it is constructed to emit ultrasonic waves upon being electrically stimulated, while generating electrical signals when being acoustically stimulated. Also conventional is the use of electronic circuitry in con-~unction with that transducer including particularly circuitry which switch-es over ~rom the transmitter mode to the recei~er mode once an ultrasonic pulse has been launched.
'~he transducer is contained in a sleeve 3 for purposes of mounting.
The front of the sleeve projects beyond the transducing surface 2'. Con-ceivably, the space adjacent to that surface 2' is filled with water during test operations. The front end of that sleeve may engage the test ob~ect, however5 the inter~ace may be somewhat fur-ther away still. The sleeve should have poor propagati~e properties as to acoustic waves, or at least may be provided with some attenuating means, so -that ultrasonic ~a~es are b3~
not launched via the sleeve 3. A relati~ely thin wire 4 is placed dia-metrally across -the space in ~ront of surface 2', and at a particular1 well defined distance therefrom. The area covered by the ~ire 4 in front of sur-~ace 2' is small in relation to -the area of that surf'ace. Since the prop-agation path from the vibrating element to the wire has good propagative properties, there is little attenuation and a ~inite amoun-t of acoustic en-ergy i5 reflected back to the transducerO That amoun-t will produce a de~-inite response, i.e. it is suf'~iciently strong, being, as far as the ampli-tude is concerned, o~ the order of flaw echos, which the transducer may recei~e when coupled to a test ob~ect. On the other hand, the partial re-~lection on wire L~ diminishes the launched energy to a ~rery small extent only so that the test is not inter~erred wi-th.
In operation, the head is depicted, i~e. including its calibration reflector element 4, is installed in the test equipment which is now cali-brated in situ. The response o~ the electronics, with head installed, to the echo from the wire is and remains an operating parameter. During test runs there will always be an echo ~rom wire 4 so that the equipment can be recalibrated whenever needed.
The echo can actually be used in each test cycle as one o-~ the measuring parameters. Slnce the wire 4 is also spaced ~rom the interface between, on one hand, the transaucer and the coupler ~luid, and~ on the other hand~ the test obJect, the echo from wire 1I can readily be distin-guished ~rom any other echos on the basis o~ the transit time. The wire echo will occur at a rather precisely de~ined period of time following launching and positively before~ e.g. a ~ront wall echo on test objects' sur~ace. The wire ~ must be spaced su~iciently ~ar ~rom sur~ace 2' so that the transducer can readily be switched in time ~rom the transmitter -to the receiver mode. Also, the transducer as such should have recovered be~ore the calibration echo arrives.
Since the calibration ~eature becomes a permanent part o~ the test head, there is an inheren-t compensation oP any manufacturing tolerances.
Also, any external interferences with the operation can readily be recog~
nized by, e.g. a change in the amplitude of the calibration wire echo.
Moreover, the initialization and set up procedure oP the test equipment is shortened.
Figure 2 illustrates a variant in the construction -to be used either when coupler fluid is not employed or i~ one does not wish to extend any coupler fluid directly to the active transducing surface 2'. The trans-ducer jacket has been extended here in forward direction, though a sleeve, such as 3 of Figure 1, could also be used. The front end of the transducer jacket is filled with a plastic material 6 of particular acoustic properties.
The material should not attenuate the acoustic energy, exhibit little dis-persion and should not tend to reverberate. One can use here, for example, material sold under the trade mark "Plexiglas".
The material 6 is provided simply with a bore 5 extending in dia-metrical direction across the space in Pront oP the transducing surface 2' and also at a well de~ined distance there~rom. The bore 5, in this case, acts as a calibration and reference reflector just as wire L~ in Figure 1.
~he advantages and Peatures outlined above are also applicable here.
ZO l~e invention is not limited to the embodiments described above but all changes and modifications thereof not constituting departures from the ~pirlt a d scope of the invention are intended to be included.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Transducer head for ultrasonic testing of structural materials having a transducing surface, comprising:
a means for defining an acoustic wave propagative path in front of the surface; and a calibration reflector disposed across the path in front of the said surface and at a distance therefrom for intercepting a central portion and reflecting a small portion of any ultrasonic energy launched by the transducer, but permitting the major portion of that energy to pass said reflector on both sides due to the extension of the reflector across the path of the energy.
a means for defining an acoustic wave propagative path in front of the surface; and a calibration reflector disposed across the path in front of the said surface and at a distance therefrom for intercepting a central portion and reflecting a small portion of any ultrasonic energy launched by the transducer, but permitting the major portion of that energy to pass said reflector on both sides due to the extension of the reflector across the path of the energy.
2. Transducer head as in Claim 1, said reflector being a wire.
3. Transducer head as in Claim 1, there being an acoustic energy transmissive material in said path, said reflector being a bore in the mater-ial.
4. Method of operating an ultrasonic transducer for testing structural materials, including coupling the transducer to a test object, the trans-ducer being connected to test electronics, the improvement comprising:
providing a permanently installed reference reflector between an active transducing surface and the test object, spaced from both of them and extending across a path from the transducing surface for intercepting a central portion of a beam of ultrasonic energy when launched by the transducer;
extracting echo signals from the transducer, resulting from the reflection of ultrasonic energy by the reflector, including distinguishing the echo signal from others on the basis of transit time difference; and using the thus distinguished echo signal for calibration, including calibration of the response of the test electronics.
providing a permanently installed reference reflector between an active transducing surface and the test object, spaced from both of them and extending across a path from the transducing surface for intercepting a central portion of a beam of ultrasonic energy when launched by the transducer;
extracting echo signals from the transducer, resulting from the reflection of ultrasonic energy by the reflector, including distinguishing the echo signal from others on the basis of transit time difference; and using the thus distinguished echo signal for calibration, including calibration of the response of the test electronics.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2726400.2 | 1977-06-09 | ||
| DE2726400A DE2726400B2 (en) | 1977-06-09 | 1977-06-09 | Ultrasonic test head |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1112352A true CA1112352A (en) | 1981-11-10 |
Family
ID=6011302
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA305,016A Expired CA1112352A (en) | 1977-06-09 | 1978-06-08 | Test head for ultrasonic testing of structural material |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4238963A (en) |
| JP (1) | JPS545485A (en) |
| CA (1) | CA1112352A (en) |
| DE (1) | DE2726400B2 (en) |
| FR (1) | FR2394083A1 (en) |
| GB (1) | GB1604970A (en) |
| IT (1) | IT1094572B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4445360A (en) * | 1982-04-01 | 1984-05-01 | Western Electric Co., Inc. | Method for ultrasonically determining characteristics of a body |
| HU191162B (en) * | 1985-01-07 | 1987-01-28 | Vasipari Kutato Es Fejlesztoe Vallalat,Hu | Test body for evaluating the results of non-destructive testing as well as method for producing test bodies |
| EP0237882A3 (en) * | 1986-03-19 | 1989-07-26 | INTERATOM Gesellschaft mit beschränkter Haftung | Method for long-duration monitoring of metallic construction elements with ultrasonics |
| JPS6445063A (en) * | 1987-08-12 | 1989-02-17 | Matsushita Electric Ind Co Ltd | Thermal battery equipped with piezoelectric starting equipment |
| JP6463920B2 (en) | 2013-08-05 | 2019-02-06 | キヤノン株式会社 | Ultrasonic transmission device, ultrasonic reception device, sheet discrimination device and image forming device |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2869108A (en) * | 1949-12-09 | 1959-01-13 | Jr Louis E Smith | Sonic radio link wave height meter |
| US3184969A (en) * | 1963-06-10 | 1965-05-25 | Gen Signal Corp | Liquid level indication system |
| US3677061A (en) * | 1971-02-10 | 1972-07-18 | Amsted Ind Inc | Ultrasonic test standard |
| US4130018A (en) * | 1977-08-30 | 1978-12-19 | Envirotech Corporation | Ultrasonic transducer with reference reflector |
| US4090407A (en) * | 1977-09-19 | 1978-05-23 | T. W. Salisbury, III | Water level measurement device |
-
1977
- 1977-06-09 DE DE2726400A patent/DE2726400B2/en not_active Ceased
-
1978
- 1978-05-09 IT IT23160/78A patent/IT1094572B/en active
- 1978-05-30 FR FR787816824A patent/FR2394083A1/en active Granted
- 1978-05-31 GB GB26004/78A patent/GB1604970A/en not_active Expired
- 1978-05-31 JP JP6561778A patent/JPS545485A/en active Pending
- 1978-06-05 US US05/912,712 patent/US4238963A/en not_active Expired - Lifetime
- 1978-06-08 CA CA305,016A patent/CA1112352A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2394083B1 (en) | 1983-11-25 |
| JPS545485A (en) | 1979-01-16 |
| GB1604970A (en) | 1981-12-16 |
| FR2394083A1 (en) | 1979-01-05 |
| DE2726400B2 (en) | 1979-05-31 |
| IT1094572B (en) | 1985-08-02 |
| IT7823160A0 (en) | 1978-05-09 |
| DE2726400A1 (en) | 1978-12-21 |
| US4238963A (en) | 1980-12-16 |
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